Epidermal growth factor-urogastrone receptors in normal human liver and primary hepatoma

The biosynthesis, phosphorylation, and degradation of the epidermal growth factor (EGF) receptor were examined in normal human fibroblasts. The receptor was initially synthesized as an Mr = 160,000 immature form which matured to an Mr = 170,000 form in a monensin-sensitive manner. Tunicamycin treatment led to the accumulation of an Mr = 130,000 protein. The receptor was phosphorylated on serine and threonine residues in normally growing and quiescent cells, and treatment with EGF or the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) resulted in a two- to threefold increase in receptor-bound phosphate. EGF increased the amount of phosphoserine and phosphothreonine and caused the appearance of a minor amount of phosphotyrosine. TPA increased the levels of phosphoserine and phosphothreonine exclusively. Prior treatment with TPA inhibited the EGF-dependent appearance of phosphotyrosine in the receptor. Analysis of tryptic phosphopeptides revealed that six of the seven major peptides were common to the receptor from cells treated with EGF or TPA. EGF strongly stimulated [3H]thymidine incorporation in confluent cells, increased final saturation density three to fourfold, and increased whole-cell levels of phosphotyrosine about threefold. Treatment of cells with TPA before addition of EGF inhibited all three of these EGF-dependent responses. EGF also decreased the receptor half-life from 15 h to 1 h, but this was not inhibited by TPA. TPA alone had no detectable effect on the receptor half-life.

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Epidermal Growth Factor-Binding Sites, Present in Normal Human and Rat Pituitaries, Are Absent in Human Pituitary Adenomas*

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jcem-65-2-275 ◽

1987 ◽

Vol 65 (2) ◽

pp. 275-281 ◽

Cited By ~ 29

Author(s):

P. BIRMAN ◽

M. MICHARD ◽

J. Y. LI ◽

F. PEILLON ◽

D. BRESSION

Keyword(s):

Growth Factor ◽

Epidermal Growth Factor ◽

Binding Sites ◽

Pituitary Adenomas ◽

Human Pituitary ◽

Factor Binding ◽

Human Pituitary Adenomas ◽

Normal Human ◽

Epidermal Growth

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Effects of epidermal growth factor and 12-O-tetradecanoylphorbol-13-acetate on metabolism of the epidermal growth factor receptor in normal human fibroblasts.

Molecular and Cellular Biology ◽

10.1128/mcb.4.9.1718 ◽

1984 ◽

Vol 4 (9) ◽

pp. 1718-1724 ◽

Cited By ~ 73

Author(s):

S J Decker

Keyword(s):

Growth Factor ◽

Epidermal Growth Factor ◽

Half Life ◽

Egf Receptor ◽

Human Fibroblasts ◽

Tumor Promoter ◽

Minor Amount ◽

Detectable Effect ◽

Normal Human ◽

Epidermal Growth

The biosynthesis, phosphorylation, and degradation of the epidermal growth factor (EGF) receptor were examined in normal human fibroblasts. The receptor was initially synthesized as an Mr = 160,000 immature form which matured to an Mr = 170,000 form in a monensin-sensitive manner. Tunicamycin treatment led to the accumulation of an Mr = 130,000 protein. The receptor was phosphorylated on serine and threonine residues in normally growing and quiescent cells, and treatment with EGF or the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) resulted in a two- to threefold increase in receptor-bound phosphate. EGF increased the amount of phosphoserine and phosphothreonine and caused the appearance of a minor amount of phosphotyrosine. TPA increased the levels of phosphoserine and phosphothreonine exclusively. Prior treatment with TPA inhibited the EGF-dependent appearance of phosphotyrosine in the receptor. Analysis of tryptic phosphopeptides revealed that six of the seven major peptides were common to the receptor from cells treated with EGF or TPA. EGF strongly stimulated [3H]thymidine incorporation in confluent cells, increased final saturation density three to fourfold, and increased whole-cell levels of phosphotyrosine about threefold. Treatment of cells with TPA before addition of EGF inhibited all three of these EGF-dependent responses. EGF also decreased the receptor half-life from 15 h to 1 h, but this was not inhibited by TPA. TPA alone had no detectable effect on the receptor half-life.

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